Venture aims to transit data from New York to Tokyo within less than 130 milliseconds

LONDON—Space startup LeoSat Enterprise LLP said it has secured its first customer for a proposed new satellite constellation promising high-speed traders and others a quicker way to complete transactions.

LeoSat is one of the latest ventures hoping to use satellites to provide high-speed connectivity to overcome perceived shortfalls in terrestrial infrastructure. The Washington, D.C.-based startup, which was founded in 2013, is in...